1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly to a semiconductor device composed of a plurality of laminated semiconductor chips having substantially the same outer contour with one another, with an integrated circuit being formed on one of the principal faces of each semiconductor chip.
2. Description of the Background Art
In recent years, in the field of semiconductor devices, so-called “system-in-package” technology has gained more importance. According to system-in-package” technology, a single semiconductor device incorporating a plurality of semiconductor chips having different functions is constructed. In addition to being downsized, a semiconductor device constructed according to this technology can provide a realize a highly functional system where the semiconductor chips are able to mutually exchange data within the semiconductor device.
A conventional semiconductor device which is constructed according to system-in-package technology is disclosed in Japanese Patent Laid-Open Publication No. 2003-23136. As shown in FIG. 18, this conventional semiconductor device has a structure such that a memory chip 1014 and a microcomputer chip 1015 are attached to each other “back-to-back”, i.e., so that a face of each of the chips 1014 and 1015 having circuitry formed thereon is facing outwards. The metal wires taken out from the memory chip 1014 and the microcomputer chip 1015 are electrically connected to each other, via a conductive common lead 1024. Thus, electrical conduction between the memory chip 1014 and the microcomputer chip 1015 is achieved.
However, in the conventional semiconductor device, the conductive common lead 1024 is composed as a separated element from external terminals 1025 and a die pad 1017, and as such, needs to be affixed by means of an insulative piece 1026 as shown in FIG. 18, in order to be stabilized in place within the semiconductor device. This results in an increase in the number of component elements used in the semiconductor device. Furthermore, in order to connect the common lead 1024 to both the memory chip 1014 and the microcomputer chip 1015 by means of metal wires, it is necessary to position the common lead 1024 precisely with respect to both the memory chip 1014 and the microcomputer chip 1015. Such a precise positioning for the common lead 1024 is a hindrance to a rapid assembling of the semiconductor device.